1. Field of the Invention
The invention concerns a pressure processing roll with a roll jacket, the roll jacket being rotatably mounted on a carrier by a bearing arrangement.
2. Description of Background Information
A pressure processing roll in which the bearing arrangement has at least one hydrostatically supported bearing surface, which forms a gap with an opposing surface, is known from German Patent No. DE 33 48 209 C2.
Such rolls are suitable for numerous applications, for example, for calenders; smoothing machines; press sections of paper, pulp, and printing machines; or rolling mills for steel, plastic, and the like. The roll works with an opposing roll such that a material web can be guided through between the two rolls and processed under pressure in the nip between the two rolls.
In this process, the roll jacket may sag. When the roll jacket sags, a nonuniform nip will develop over the axial length of the roll. However, usually, some mechanism is provided in such pressure processing rolls to oppose the sagging of the roll jacket. The mechanism may be, for example, a set of support shoes which are disposed between the roll jacket and the carrier (roll jacket carrier). The roll jacket may be alternatively provided with a hollow interior or cavity, which is subdivided into two or more chambers in the circumferential direction, the chamber adjacent to the nip being placed under the pressure of a hydraulic fluid.
Where the pressurized hydraulic fluid is used to counteract the sagging of the roll jacket, in all cases in which an elevated pressure exists in the interior of the roll jacket, it is necessary to seal the cavity or interior of the roll jacket by transverse seals of the ends of the roll. In these transverse end seals, parts which are movable relative to each other must work together, which causes significant wear. Moreover, the wear increases with the operational speed of the roll. It is not necessary, however, that the transverse end seal completely prevent the escape of hydraulic fluid. The task of the transverse end seals is rather to maintain the pressure in the interior of the roll jacket at a specific level.